why we use inheritance in java code example

Example: Inheritance in java

// Hierarchical inheritance in java
class Animal
{
   void eating()
   {
      System.out.println("animal eating");
   }
}
class Lion extends Animal
{
   void roar()
   {
      System.out.println("lion roaring");
   }
}
public class Dog extends Animal
{
   void bark()
   {
      System.out.println("dog barking");
   }
   public static void main(String[] args)
   {
      Animal obj1 = new Animal();
      obj1.eating();
      Lion obj2 = new Lion();
      obj2.eating();
      obj2.roar();
      Dog obj3 = new Dog();
      obj3.eating();
      obj3.bark();
   }
}